SNAP annotations: PDB entry 1n32

PDB-id

1n32; DSSR-derived features in text and JSON formats; DNAproDB

Class

ribosome

Method

X-ray (3.0 Å)

Summary

Structure of the thermus thermophilus 30s ribosomal subunit bound to codon and near-cognate transfer RNA anticodon stem-loop mismatched at the first codon position at the a site with paromomycin

Reference

Ogle JM, Murphy IV FV, Tarry MJ, Ramakrishnan V (2002): "Selection of tRNA by the Ribosome Requires a Transition from an Open to a Closed Form." Cell(Cambridge,Mass.), 111, 721-732. doi: 10.1016/S0092-8674(02)01086-3.

Abstract

A structural and mechanistic explanation for the selection of tRNAs by the ribosome has been elusive. Here, we report crystal structures of the 30S ribosomal subunit with codon and near-cognate tRNA anticodon stem loops bound at the decoding center and compare affinities of equivalent complexes in solution. In ribosomal interactions with near-cognate tRNA, deviation from Watson-Crick geometry results in uncompensated desolvation of hydrogen-bonding partners at the codon-anticodon minor groove. As a result, the transition to a closed form of the 30S induced by cognate tRNA is unfavorable for near-cognate tRNA unless paromomycin induces part of the rearrangement. We conclude that stabilization of a closed 30S conformation is required for tRNA selection, and thereby structurally rationalize much previous data on translational fidelity.